FIG. 1 is a view showing a conventional belt drive type laundry treatment apparatus.
The conventional laundry treatment apparatus shown in FIG. 1 may include a cabinet 1 defining the appearance of the laundry treatment apparatus, a tub 2 disposed in the cabinet 1 to contain washing water, and a drum 3 rotatably disposed in the tub 2 to contain laundry.
The cabinet 1 and the tub 2 include an introduction port for allowing the inside thereof to communicate with the outside thereof. The laundry treatment apparatus further includes a door 11 for opening and closing the introduction port.
The cabinet 1 further includes springs 4 and a damper 5 to attenuate vibrations generated by the rotation of the drum 3.
The laundry treatment apparatus further includes a power unit 6.
The power unit 6 includes a motor 64 for generating rotational force, a first pulley 62 rotatable by the rotational force generated by the motor 64, a second pulley 63 having a larger diameter than the first pulley 62, a belt 65 for causing the first and second pulleys 62 and 63 to rotate together, and a shaft 61, which is integrally formed at one end thereof with one side of the second pulley 63 and at the other end thereof with the drum 3 to transfer the rotational force generated by the power unit 6 to the drum 3.
More specifically, in order to transfer the rotational force generated from by motor 64 to the second pulley 63, which has a larger diameter than the first pulley 62, the first pulley 62 and the second pulley 63 are connected to each other via the belt 62 wound therearound. The first and second pulleys 62 and 63, which have different diameters, transfer the low-speed, high-torque rotational force to the drum 3.
The tub 2 further includes a bearing housing 22, and a bearing 21 rotatably provided in the bearing housing 22, in order to reduce the radial load generated during rotation of the shaft 61.
A conventional belt drive reduction mechanism using pulleys has a problem of generation of noise due to rotation of the belt 65. Furthermore, the reduction mechanism has a problem of breakage of the belt 65.
In addition, since space required for rotation of the belt 65 has to be ensured because the first and second pulleys 62 and 63 are provided in the cabinet 1, assembly thereof is difficult.
Furthermore, since the first pulley 62 rotates at a higher speed and the second pulley 63 rotates at a higher torque in the state in which the belt 65 is in contact with the first and second pulleys 62 and 63, friction is generated between the belt 65 and the pulleys 62 and 63, thus deteriorating the motor efficiency.
In addition, since the belt 65 is in contact with the first and second pulleys 62 and 63, there is a problem in that the motor 64 may be burned when excessive load is applied to the power unit 6.
FIG. 2 is a view showing a conventional direct-drive type laundry treatment apparatus.
The conventional laundry treatment apparatus shown in FIG. 2 may include a cabinet 10 defining the appearance of the laundry treatment apparatus, a tub 20 disposed in the cabinet 10 to contain washing water, and a drum 30 rotatably disposed in the tub 20 to contain laundry.
The cabinet 10 further includes springs 40 and a damper 50 in order to attenuate vibrations generated by the rotation of the drum 30.
The cabinet 10 and the tub 20 include an introduction port for allowing the inside thereof to communicate with the outside thereof. The laundry treatment apparatus further includes a door 101 for opening and closing the introduction port.
The laundry treatment apparatus further includes a power unit 60 for rotating the drum 30. The power unit 60 generates rotational force, and rotational force generated by the power unit 60 is transferred to a shaft 601 and is in turn transferred to the drum 30, which is configured to be rotated with the shaft 601.
The tub 2 further includes a bearing housing 202, and a bearing 201 rotatably provided in the bearing housing 202, in order to reduce the radial load generated during rotation of the shaft 601.
The power unit 60 includes a stator for generating a rotating magnetic field, and a rotor adapted to be rotated by the rotating magnetic field generated by the stator. Since the conventional direct-drive type laundry treatment apparatus shown in FIG. 2 enables only the rotation of the drum 3, it has to further include gears in order to reduce the speed and thus transfer high torque. However, since the gears are configured to transfer power in the state of being engaged with each other, there is a problem of generation of noise due to vibrations of the gears. Furthermore, when the reduction of speed is executed while the gears engage with each other, there is a problem of deterioration of efficiency.
In addition, since the gears are engaged with each other, there is a problem of burning of the motor 602.